


Glad You're Home

by PurrfecktlySinful



Category: Undertale (Video Game)
Genre: Fellcest - Freeform, Fluff, Fontcest, Light Bondage, Longing, M/M, Mating Cycles/In Heat, Oral Sex, Sensitive bones, Somnophilia, Underfell, dubcon
Language: English
Status: Completed
Published: 2016-06-22
Updated: 2016-06-22
Packaged: 2018-07-16 14:38:40
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 5,543
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7272187
Author URL: https://archiveofourown.org/users/PurrfecktlySinful/pseuds/PurrfecktlySinful
Summary: <blockquote class="userstuff">
              <p>Sans is in Heat and Papyrus is not at home to help him.</p>
            </blockquote>





	Glad You're Home

**Author's Note:**

> [MY TUMBLR IS HERE](http://purrfecktlysinful.tumblr.com)
> 
>  
> 
> Again big thanks to the following for editing help, word suggestons, encouragement, etc:
> 
>  **Undertailsoulsex** ([Tumblr](http://undertailsoulsex.tumblr.com)/[AO3](http://archiveofourown.org/users/undertailsoulsex/pseuds/undertailsoulsex))  
>  **Psycho4sans** ([Tumblr](http://psycho4sans.tumblr.com)/[AO3](http://archiveofourown.org/users/psycho4sans/pseuds/psycho4sans))  
>  **Eiznel24** ([Tumblr](http://eiznel.tumblr.com)/[AO3](http://archiveofourown.org/users/Eiznel24/pseuds/Eiznel24))

Sans was used to nightmares. They visited him often, sometimes multiple times in a night, causing him to jolt awake with a low cry or gasp, breathing heavily, trying to capture whatever wispy-vague image had caused him such alarm. He could never fully grasp those dreams...vague impressions of snow and dust and children with knives...of crimson fabric on white snow and an overwhelming sense of loss that left him sick on waking. He could handle those. Breathing deeply, he would urge his shuddering soul to calm before turning back over and returning to a restless sleep. 

But not tonight.

These were definitely not nightmares. They were muzzy and almost suffocating, full of light touches and a close warmth that left him panting and whining. The feeling of being pinned, the sensation of hands running over his ribs, clawing and scratching as he writhed beneath them, needy for more. The tension increased until his mind couldn't take it anymore, breaking through the surface of his dreams like a drowning creature gasping for air. Half awake, he could feel his clothing and blankets wrapped tightly around him, tangling his limbs and clinging to his body. As he became more alert, he wiggled and kicked out in frustration, eventually maneuvering the blankets off of him and into a damp clump at the end of his bed. Now fully awake, he lay there, splayed out on his worn mattress, breathing heavily and staring at his ceiling in a daze.

This was just pure misery.

His magic was an absolute mess, roiling within him in search of some outlet.

His bones itched and crawled.

His soul and pelvis throbbed insistently, almost painfully in time with each other.

And above all, he was so unbearably, relentlessly HOT. 

Being in heat was fucking uncomfortable.

Usually Papyrus was around to help. Sans could always count on his Boss for a few rounds of good, solid fucking to get it out of his system. It was one of the few thing he did for Sans without any resistance or argument. And boy did Papyrus have the stamina for it. His energy seemed to go on forever, and where most monsters would have been overwhelmed into senselessness by another monster's heat, Boss was always under control, outlasting Sans each and every time. He almost seemed to take it as a personal challenge.

But not this time.

No, this time Boss had felt the need to take most of the fucking Peanut Parade out on some God-forsaken training exercise. And of COURSE neither of them had bothered to remember that it was close to San's heat cycle. Papyrus' one concern had been to beat some sense and order into his subordinates. So Papyrus had gone, leaving Sans with the usual abrasive reminder to "REMEMBER NOT TO FUCK UP TOO BADLY WHILE I'M AWAY." 

Sans had shrugged, giving Papyrus his usual cocky smile and raised eye ridge.

"got it, Boss."

Sans, with his hands shoved in his pockets, was preoccupied only with the fact that Papyrus was leaving him alone for a straight WEEK. He was still trying to decide if this was a good thing or not. On the one hand, no nagging, no yelling, he could shed his clothing wherever the fuck he felt like and eat out every day at Grillby's if it so pleased him. On the other hand, the house seemed eerily quiet whenever Boss was gone, and in the fucked up world they lived in there was always something to be said for safety in numbers.

And now here he was, just a fucking DAY away from when Boss was due to return, flopping around on his bed as his heat ripped through him relentlessly. He could handle this. He just had to ride this the fuck out and everything would be just fine. After all, he had taken care of heats long before Papyrus had ever been aware they existed. He would manage.

He'd be fine...He would be totally...

A wave of burning, shivering prickles radiated outward from his soul and over his bones, almost unbearable in its intensity. Sans gave a low groan, squirming on his mattress. He felt his cock coalesce and harden in his shorts, begging, SCREAMING to be touched. He couldn't take it anymore; he had to have some kind of relief. 

Clumsily Sans fumbled at his shorts, slipping his hand under the band and wrapping his fingers around his length, already slick with the precum that had dribbled from the tip and down the side. Just the contact from his hand caused Sans to arch his back, his hips bucking, seeking any kind of respite from the raging lust in his bones. Not bothering with any kind of buildup, he began moving his hand in quick jerking movements, his only concern being to get himself to his climax as quickly as possible. His desperate noises filled the room as he jerked himself off, small jolts of pleasure radiated up from where he was stroking himself. 

In his mind he only saw Papyrus, his Boss. Papyrus, kissing him greedily. Papyrus, running that hot tongue along his bones...Papyrus...Using that same tongue on his cock...Papyrus...here...with him...

"nnngahh...FUCK...Papyrus!~"

His orgasm rippled up through his bones, his mind going blank before he collapsed back in a shuddering mess. He lay panting for some time after that, waiting for his thoughts to clear. Finally, with a loud groan he sat up, rubbing at his skull with one hand.

He was still so FUCKING hot!

At least now he could think, though that would only be temporary. The raging inferno of his heat had only subsided into a robust blaze. He had cracked his window earlier and now he peeled his shirt off, urgently needing to feel the cold Snowdin air on his bones. The effect was slight at best. He also felt parched. Well, that, at least, he could take care of. 

Standing and making his way out of his room, he headed towards the kitchen. Sans slowly moved through the house, having to pause periodically to wait for small waves of burning to pass over his study frame. He tried hard to keep his mind as focused as possible on his goal. End of the hall...great. Bottom of the stairs...wonderful. At last, the kitchen...a fucking MIRACLE.

He stood unsteadily on his feet in the door of the kitchen, hand gripping the door frame tightly, taking a moment to process what needed to be done next. His soul pulsed brightly, lending its glow to the dark kitchen, eliminating the need for sans to flip the light switch on. He needed a drink...

How had he managed this when Boss was around? He didn't recall exactly, heats didn't exactly lend to clear thinking. Somehow, though, he remembered that in the small spaces between surges, a glass of water had somehow just BEEN there on the table next to his bed, always chilled as though it had come straight from their fridge. 

The fridge.

Sans shuffled over to the fridge, opening it to check inside. A blast of chilled air hit him in the face, and he simply stood there for a moment, enjoying the play of the iced air across his bones. Better than the open window, but still not nearly enough. Attempting to focus once more, he scanned the inside of the fridge, and saw a familiar flash of yellow.

With a small croak of almost-joy, Sans lurched forward to grab the familiar yellow container from the shelf. He stuck the tip of the mustard bottle into his mouth and tipped his head back, squeezing hard.

And got nothing.

Sans blinked.

"DAMMIT!"

Sans slung the empty mustard bottle across the kitchen, where it thumped hollowly against the wall before falling uselessly to the floor. Of COURSE it was empty. Papyrus was always the one who did the shopping, and he wasn't here. Since Sans had spent the better part of the week eating out at Grillby's he had never thought to go out to shop for food himself...he figured that Boss would just take care of it when he came back.

Peering back into the fridge, his eyes landed on the only other liquid present within, a half-quart of milk. Papyrus was fond of the stuff, once spouting some bullshit about it helping him to battle-harden his bones and keeping him in top fighting form. Sans hadn't seen the need at the time to tell him that he didn't think the same principles of bone-health applied to magic skeleton-monsters as it did to humans. Didn't care for the stuff himself, but at this point he'd probably drink KETCHUP and like it.

He grabbed the cardboard container. Boss was gonna be pissed to find his milk gone, but it was his fault for taking off for a fucking week when Sans was due to be in heat. He brought the container to his mouth, chugging the stuff down and trying to ignore the taste. A few drips of the stuff escaped and dribbled down the side of his face.

It helped about as much as he thought it would...which wasn't much.

He lobbed the empty container at the trash bin, missing entirely. He left it. He really couldn't care less right now. He just wanted to get back up to his room where he could continue being miserable in peace. 

As he slammed the door to the fridge shut, he thought he saw something out of the corner of his eye.

Red.

Sans turned to the counter, trying to focus his hazy vision on the object he had spotted.

Gloves.

Red gloves.

Boss' red gloves...

Those hadn't been there earlier. Sans was positive. Not only that, but Papyrus NEVER left those things behind when he left the house.

Boss was home?

When had that happened?

The fact that Papyrus had left his gloves just laying out like this said a lot. The only time that obsessive neat-freak forgot ANYTHING was when he was falling down exhausted or sick. Knowing the bullshit he likely had to deal with on his little training trip, Sans was fairly certain that Papyrus was currently passed out in his room, trying to recoup some energy before charging back to his Royal Guard duties the next day.

Meaning it was best to let sleeping skeletons lie.

A particularly strong surge washed over him, and his knees almost buckled. Just the thought of Papyrus being in the same house with him was setting his magic off. If he could just get to his room... Once there, he could suffer on his own till his heat dissipated.

Leaving the kitchen, he limped up the steps to the second floor, pausing again as another wave of heat rolled over him, his hand clenching, fingers digging into the banister and leaving marks in the finished wood. Damn that was a bad one. He was half tempted to beat one off right there on the stairs, just to get some form of relief, but he thought better of it. He was not all that far from his room now...just a little more. 

He stopped at the top of the stairs, right in front of Papyrus' room. 

Ok...his own room was just down the hall.

He took another step towards his brother's door.

As though watching from a distance, his mind argued violently against what his body was doing. No! Papyrus was exhausted. He needed to rest! He would kick Sans' ass for even THINKING of waking him at this time of night!

His hand was on the doorknob, turning it slowly, quietly.

The door swung open. Sans stepped through into Papyrus' room, the pulsing glow of his soul lighting the way.

Papyrus' room was as neat and tidy as it always was, the only exception being that his battle outfit was flung in a small heap at the foot of the bed. Sans approached and gazed down at the rumpled mess. Damn, they must have really run his brother through the wringer if he didn't even bother to pick his clothes up off the floor. The only article of clothing that had been saved from this cruel fate was his scarf, which was draped casually over the foot of Papyrus' bed. Without thinking, he picked it up, examining the tattered and frayed ends. His bones were sensitive and he liked the feel of the fabric between his fingers.

He moved around to the side of the bed and looked down at Papyrus. The glow of Sans' soul illuminated his brother's sleeping form, playing across his features and bathing his bones in red. It suited him so well, the fierce color of fire, blood and determination. The blanket was only pulled halfway up, his shirt slightly rumpled, tantalizing peeks of bone showing through here and there. Sans' eyes traveled down the graceful curve of Papyrus' neck to the small flash of white under his collar down to where his lowermost ribs and spine were just visible under the hiked up edge of his shirt.

Sans felt another wave of lust roll through his bones. 

Fuck it.

His thoughts became an almost inaudible whine in the back of his mind. They futilely insisted that there was no way...Boss would wake up...there was just no fucking way!

The mattress gave softly under his weight as he climbed up at the end of the bed, eyes trained constantly on his brother's still form, looking for any sign of movement. Gradually he pulled at the blankets, sliding them down off of his sleeping brother. He paused. Nothing but stillness. Papyrus was truly dead to the world. Sans slowly and cautiously crept up from the foot of the bed, taking all care not to make any exaggerated motions, till he was astride Papyrus' waist.

He sat up, looking down on his sleeping brother. It wasn't often he got to see Boss like this...sleeping...unaware...vulnerable. One arm was carelessly flung above him on the pillow and the other resting across his chest, rising and falling with his slow breaths. His scarred face, normally creased in a stern scowl was relaxed and peaceful. Under normal circumstances, it would have been one hell of a turn on. However, the way Sans was currently, it was like pushing him over the edge when he was already falling to begin with.

Sans realized he still had Boss' scarf in his hand.

He had an idea.

He was probably gonna get his ass kicked, but he was sure as hell gonna make sure he got to finish first. 

Moving as quickly as his hazy thinking would allow, he took hold of his brother's hand and brought it up to meet the other above his head, where he quickly wrapped the scarf around them. Remembering something Boss had done on another occasion, he then pinned them with a bone construct. Papyrus shifted restlessly, turning his head and uttering an incoherent grumble. Sans retreated a bit, moving lower and straddling one of Boss's legs, with his knee just barely brushing at the junction of Papyrus' legs.

Now that Sans was relatively sure he wouldn't be interrupted, he wasted no time. Leaning forward, he slid his hands up under Papyrus' shirt, hooking the hem with his thumbs and drawing it up to expose his ribcage, fingers trailing over his lithe and powerful frame. Sans eyes traveled hungrily, chasing the edge of the shirt, lingering on every scar, chip and hairline crack scattered across Papyrus' bones. Each perfect blemish was a testament to his strength and fighting prowess.

Fuck, Boss was just too cool.

Just this limited contact had an effect, soothing some of the discomfort in his bones as he pursued the pleasure that would quench his heat. He could sense Papyrus' magic in the bones beneath his hands and his soul yearned to mingle that fierce energy with its own.

Papyrus shifted slightly beneath him, reacting to the touch with a breathy groan. Sans' soul hitched at the noise. Now that was a nice sound. His eyes flicked up to see that Papyrus' face was creased slightly...as though he were dreaming...

Sans figured that dream was about to get a HELL of a lot more interesting. 

He allowed the heat to lead him, giving him a confidence he never would have had otherwise. Leaning in, he allowed his tongue to join his hands, playing over the ivory bones before him. He could feel his fingers and tongue catch lightly on the deeper scores in Papyrus' bones, and he traced along them almost reverently, giving them extra attention.

Memories of where some of those scars had come from burned in his mind. Here, where Undyne's spear had grazed Papyrus' side as he battled her for leadership of The Royal Guard. Along his sternum, where he had been badly scored by an escaped criminal he had cornered. The crook of his neck, where a foolishly drunk dog monster had bitten him. Sans explored every last one, small wet shocks of energy sparking like static electricity from his tongue as the pent up magic within him tried to escape. He could feel Boss' breaths quicken, could hear the rush of air as he began to gasp breathlessly in his sleep, his movements becoming more pronounced and frequent. Sans' soul began to beat more quickly...how long, he wondered...it was only a matter of time...

Waves of pleasure continued to pulse outward from Sans' soul, traveling along his bones in warm tingling waves as it resonated, calling to Papyrus' magic, urging it to respond to his own. Sans thought he saw a faint pulse from below Papyrus' sternum in response.

As though to tempt fate, his fingers trailed down, over Boss' floating ribs and then under and up again into his ribcage, rubbing along the more sensitive inside edges of the bone. Unlike the outside, the bones here was unmarred, pristine, and Sans' fingers glided effortlessly across them, bone scraping lightly on bone. The contrast was captivating. His other hand found its way to his brother's spine, languidly running up and down the elegant column, caressing the alternating contours of hard bone and softer cartilage. 

"HNG.."

Boss grunted softly, his spine arching up into Sans' touch. Sans withdrew his tongue momentarily and grinned in satisfaction at his brother's response. It was so satisfying, making him squirm in his sleep like this. Seeing this side of his brother was rare, prone and completely subject to his whims. If it weren't for the prodding need in his soul, Sans would have taken more time to soak it all in. As he had continued to work, he had felt the bulging heat of Papyrus's magic below grow against his leg. Bringing his knee in more firmly, he used it to rub at the tent in his brother's pants, rocking gently into him. Papyrus' eyes began to flutter, opening groggily and staring down in brief confusion.

"HUH...SANS...WHAT?" Papyrus muttered, his voice thick with sleep.

Sans chuckled, his eyes never leaving the glow between Papyrus' legs.

"yeah, Boss, it's me." 

Sans moved lower, hooking his fingers on Papyrus' pants. He began to tug....

"WHAT THE HELL ARE YOU DOING, SANS?"

The sharp note of command made Sans stop in his tracks, though only barely. The heat in his bones raged at being denied, even briefly, making him shudder. He looked up at Papyrus, meeting his piercing red eyes in the darkness, fully alert and glaring venomously down at him.

Fuck, what those eyes did to him.

Sans smirked.

"i, uh, think it's pretty obvious what i'm doing"

He watched as Boss tugged at his bound hands for a moment, finally realizing he had been restrained. A look of surprised outrage crossed his face, before glaring back down at Sans. When he spoke again, there was a dangerous edge to his voice.

"SANS, UNTIE ME NOW!"

Sans, confident that Boss wasn't getting loose anytime soon, resumed pulling at his brother's pants, lifting the hem and bringing it down to reveal the crimson magic that had formed itself into Papyrus' cock. Sans stared hungrily.

"sorry, Boss, but I'm not finished yet."

"FUCK YOU!" Papyrus snarled.

Sans paused and gave Papyrus a look blazing with need.

"that's kinda the point here, Boss."

Saying this he reached up to cup his brother's throbbing member in his hand, fingers gliding up the shaft and brushing teasingly over the tip. He heard Papyrus breathe in sharply. The look in his brother's eyes began to change, no longer filled purely with outrage as he stared at Sans, cheekbones beginning to flush red. Leaning in once more, Sans rested his cheek against the pulsing magic, nuzzling into it and feeling it tingle against his cheekbone, his eyes never leaving Papyrus' face. The smell of it was intoxicating, and Sans' grinned hungrily as his magic flared in response, causing him to give a low groan as his urge built within him. 

Keeping their eyes locked, Sans' tongue snaked back out and he ran it in a slow wet stripe up the underside of his brother's erection, enjoying the feel of its solid heat sliding against his face as he drew his tongue upward. Reaching the tip, he swirled around the head, tasting the precum that had gathered there before drawing slowly back down again, curling teasingly around the shaft. All the while his hand continued to work, stroking and applying pressure here and there, feeling his brother continue to harden under his touch. He watched as Papyrus alternated between throwing his head back, cursing and gasping, and raising it to glare back at him, his expression increasingly filling with lust. Sans could occasionally hear the soft sounds of Papyrus tugging at the scarf around his wrists, trying to break free but unwilling to struggle hard enough to damage the worn thing.

Sans moved his grip to the base of his brother's cock as his tongue made a final path upwards back to the tip. Once there, he paused for the barest of moments, giving Boss a smug, meaningful look before opening and taking his brother into his mouth. 

"HAHH!...FUCK...SANS, YOU ASS!"

He felt Papyrus jerk, his hips bucking upwards, catching Sans off guard and nearly making him choke. Bringing his hand up from where it had been caressing inside of his brother's femur, he placed it on Papyrus' pelvis to keep it in place. This was not going to go the way Boss wanted. This time, Sans was in control, and he would go as fast...or not...as he pleased.

The pulsing of Sans magic intensified and seemed to synchronize with the beat of his brother's. He relished the feel of Papyrus' length as it filled his mouth, sparks of energy dancing across the surface of his tongue wherever it glided along the shaft. It became slick within his mouth, the ever present thirst that had plagued him ebbing as he bobbed his head in an even rhythm. The wet sounds as he licked and sucked on his brother filled the small space between them. He moaned at the desire that flowed through him, the sound a low rumble in the depths of his conjured throat that vibrated up through his tongue and along his brother's cock. The bones under him shivered and twitched at the stimulation, and the sound of Papyrus' poorly concealed moans drifted to his ears in the dark, lancing straight through him to his core. Knowing that his brother was making such noises for him, his pride and iron will losing out against what Sans was doing to him...

Sans could feel the ache in his pelvis increase steadily, his magic coalescing according to his desires to form an entrance, pulsing with its own need. He was already wet, and he felt some of that wetness trickle down the inside of his femur, drawing a burning trail against the oversensitive bone. The craving in his middle continued to coil, demanding to be filled...to be satisfied.

He released his brother, sucking in lightly as he withdrew and allowing his tongue to linger enticingly over the head as he let go. Bones rattling softly, he clumsily removed his shorts, exposing his pelvis to the cooler air of the bedroom. On arms and legs shaking with the overpowering desire, he lurched forward until he was straddling Boss' pelvis, knees to either side. Taking Papyrus' chin in his hand, he leaned in close enough to feel the hot puffs of his brother's breath against his face.

"heh. you taste real good, bro."

San's ran his tongue across Papyrus' teeth, a silent request. His brother looked at him defiantly, his face flushed a beautiful shade of red. He didn't speak. Apparently the Great and Terrible Papyrus wasn't going down without a fight.

"don't be like that, Boss. c'mon..."

Sans adjusted his grip on his brother's chin to pry a finger into his jaw, forcing Papyrus to open to him. There was little resistance. Once he had enough space, Sans kissed him, his tongue eagerly invading and mapping out his brother's mouth, the wet heat and taste of his brother driving out all thought. All that was left was him, his brother and the ecstasy that sparked between them. It was his world, his universe. Papyrus retaliated by wrapping his own tongue around his, trying to force his way back into Sans' mouth. But Sans' heat was too much for him; he finally gave in, relenting and melting into the kiss. He allowed Sans to ravage his mouth thoroughly, their muffled noises increasing in urgency.

The ache had grown unbearable. Sans parted their kiss with a needy whine, his hips rocking desperately. He gave his brother a pleading look.

"boss...i can't...i need...please...Pap..."

Papyrus stared at him for a few moments, looking entranced. Catching Sans completely off guard, his brother suddenly leaned forward the small distance between them to place a skeleton kiss on his brow. There was a pleasant burn where his teeth had touched the oversensitive bone between San's eyes, and he drew away with a smug look.

"GO ON. DON'T DISAPPOINT ME."

Sans didn't need a second invitation. Reaching behind him, he took his brother's length in one shaking hand. He took only the barest of moments to line up, feeling the brush of the head against his opening before driving forcefully back and seating himself fully on his brother's cock. A hot shock of ecstasy lanced thorough him, and his spine arched as he keened loudly with the combined bliss and relief of feeling Papyrus' magic stretching his walls and filling him completely. There were tears in his eyes and somewhere, faintly, he thought he heard his brother also cry out. Tipping backwards, he barely managed to catch himself with his hands on Papyrus' femurs.

Overwhelmed, Sans remained like that for some moments, taking deep, shuddering breaths. 

"SANS!"

Boss' voice snapped him out of his daze and he looked down at Papyrus, who was glaring up at him in irritation, panting and pulling tightly against the scarf around his wrists.

"MOVE ALREADY YOU LAZY FUCK!"

So impatient. Sans grinned.

"heh.....got it, Boss."

Bracing himself with his arms, he began to move, rising and falling, relishing the feeling of his brother within him, sliding along his walls. He set a frantic tempo, moaning loudly each time he brought his hips back down, grinding into his brother repeatedly, his heat driving his aching need to find release. His soul beat in rhythm with his movements, becoming more frenzied as the coil of magic within it continued to tighten. His arms tired quickly and, unable to maintain his current position, he fell forward once more to support himself instead against his brother's chest. The change in position angled Sans' hips in such a way that Papyrus was suddenly hitting the deepest parts of him, and Sans' cries increased in pitch.

"Boss...so good...oh god...Papyrus...."

He could hear his brother's answering moans from beneath him, grunting and swearing loudly as Sans continued to ride him. The sounds his brother made washed through him, spurring him to move faster, chasing their spiraling pleasure to its inevitable peak. He could feel the warmth rising from his brother's soul, just beneath his ribs, glowing brightly. The sounds of Papyrus pulling at his restraints intensified as he also approached his limit.

"FUCK...SANS...MNAA...HAH..."

Finally the coil snapped, and Sans' soul flared brightly as he orgasmed, his walls clenching around his brother as rode through it. His mind was filled only with the rolling ecstasy that washed over him in waves, his bones rattling loudly as he shook with the intensity of it. He was vaguely aware of his brother straining up into him as he also climaxed, filling him with the familiar, comforting warmth of his release.

Finally, the burning energy of his heat relented and Sans slumped in relief against his brother. He pressed close to him, enjoying the soft radiance of Papyrus's soul in its afterglow as their magic dissipated. His mind was still pleasantly blank, and he counted the breaths shared between them as they both allowed themselves to wind down from their high.

"YOU'RE IN HEAT."

It wasn't so much a question as a statement of fact. Leave it to Boss to cut through the bullshit. Sans tensed.

"yeah...uh...sorry about that" he replied

"SINCE WHEN?"

"uh...yesterday, i think?"

Another silence. Papyrus' voice came to him through the dark once more.

"THEN YOU'RE NOT FINISHED YET."

Sans propped himself up on his arms and looked at Papyrus, who was watching him with his usual stern, impassive expression. He was right, though. Sans could already feel the prickles beginning to slide over his bones again as the heat began to build again in his soul. However, he could also see the dark circles under his brother's eyes, and a wave of guilt washed over him.

"listen, Boss...i know you're tired...and i'll be fine, really...i'll just.."

"SANS!"

Sans flinched at the sharp tone in his brother's voice.

"uh, yeah, Boss?"

"UNTIE ME."

Oh shit! Sans had forgotten that Papyrus was still restrained. 

"fuck! I'm sorry, Boss. here...let me just..."

Sans dismissed the bone construct pinning his brother's bound hands. Working at the scarf around his wrists with fumbling fingers, he finally managed to loosen it and pull it free. The moment Papyrus was liberated, there was a sudden lurch, and before Sans could react, the world tilted and spun as he was effortlessly flipped over and pinned by his younger brother.

Sans struggled for a moment before realizing his efforts were getting him nowhere. Ceasing all movement, he looked away, bracing himself for whatever punishment his brother would see fit to give him.

"LOOK AT ME, BROTHER"

Startled, Sans looked up. While he used to hear it all the time when they were baby bones, Papyrus almost never called him 'brother' nowadays. Acknowledging your family in such a dangerous world might give someone the impression that you were soft...that you cared. Papyrus continued.

"I, THE GREAT AND TERRIBLE PAPYRUS, WOULD BE NEGLECTING MY RESPONSIBILITY IF I DID NOT TAKE CARE OF THIS MATTER...AFTER ALL," Papyrus smirked "WHAT WOULD YOU DO WITHOUT SUCH A COOL GUY TO TAKE CARE OF YOU?" 

Sans flushed. This was about as close to an apology as Boss had ever gotten, and it made his soul skip a beat. He tried once more to protest.

"i, uh, don't know Boss...really, though, i..."

Papyrus interrupted him sharply. 

"SANS, YOU ARE GOING TO LAY THERE AND LET ME PROPERLY FUCK YOU TILL YOUR HEAT IS COMPLETED, AM I CLEAR?"

Sans met his brother's stubborn glare. It was pointless to resist when he was like this. This was one of those times when Papyrus absolutely was not going to take "no" for an answer. Giving the battle up as lost and falling back on old habits, Sans grinned at his brother insolently.

"okay. okay. i guess if i get a turn, you should too." 

"GOOD. I DO HAVE TO SAY, THOUGH," Papyrus mused "THAT I HAVE NEVER SEEN YOU LOOK SO...CONFIDENT BEFORE, BROTHER..." Papyrus brought his hand up to cup Sans' jaw, his sharp thumb rubbing lightly along his cheek. Sans pressed into it, craving the touch. Papyrus' heated eyes, glowing crimson on deepest black, pierced through him, sending pleasant shivers up his spine.

"oh? did i give you another BONER, Boss?" He quipped, his sharp grin tilting up slightly at one corner as he gave his brother a sly wink. As the familiar weight of his brother pressed against him he was already becoming conscious of the fog of his heat as it began to slide back over his mind.

Papyrus snorted.

"DON'T GET AHEAD OF YOURSELF, WHELP." 

And as Papyrus leaned in to drag his tongue over his brother's neck, Sans succumbed completely to both the heat and his brother. Beneath the haze, one thought alone pulsed within his soul.

It was good to have him home.

**Author's Note:**

> Dude! 250+ followers on Tumblr? 600+ kudos on Sunlight and Shadow?
> 
> I just...I don't....where do all you people come from!? (o//_//o)
> 
> Seriously, though, thank you all SO MUCH for being willing to entertain the self indulgent stories of this anxious little nerd. In return for your support, here! have some Underfell smut! <3


End file.
